Scraper blade assembly for the interior side wall of a grease kettle



y 0, 1958 J. R. WILSON 2,834,977

SCRAPER B ASSEMBLY FOR THE; I RIOR SIDE LL. OF A GREA SE KETT iled July 11, 1955 INVENTOR. Jase v6 R. Wilson United States Patent'O' SCRAPER BLADE ASSEMBLY FOR THE INTERIOR SIDE WALL OF A GREASE KETTLE Joseph R. Wilson, Merriam, Karts, assiguor to Stratford Engineering Corporation, Kansas City, Mo., a corporation of Delaware Application July 11, 1955, Serial No. 521,082

9 Claims. (Cl. 15246.5)

This invention relates to scraper blades for grease formulation kettles and refers more particularly to a scraper blade assembly wherein is provided a free-floating, self-adjusting scraper blade which will not change its position relative to the grease kettle wall despite eccentric motion of the scraper frame.

In grease formulation kettles, the internal scraper blades, which are mounted on a scraper frame in the kettle, are required to perform two main functions. In the first place, during the steps of manufacture, small quantities of additives are combined with oils and soaps in the paddle kettle. Some of these, together with heterogeneous parts of the soap, may cling to portions of the wall and not become well dispersed. The scraper blades should remove all portions of such additives from the wall and return them into the central mixing zone. Secondly, since grease, even in thin films, has a high resistance to heat flow, the film of grease adhering to the inside wall of the jacketed kettle reduces the heat transfer, both in the heating and cooling steps of manufacture. It has been found that the time required to heat or cool a quantity of grease in the kettle may be reduced as much as one-half by the use of good scrapers which effectively remove such films.

In the light of these facts, therefore, it is imperative to good design to have a scraper which will remove nearly all of the grease from the Wall of the kettle in the scraping process. In the past, this has been accomplished by a design wherein a scraping blade comprising a kettle wall abutting plate having a leading toe portion and a following heel portion is directly and rotatably hinged to a rotating scraper frame, said scraper blade having no freedom of translation (motion without rotation around the hinge) relative the driving scraping frame. Since the conventional scraper blade is ground to the precise radius of the vessel wall, any eccentricity of the scraper frame relative the kettle shell will cause the scraper blade to rock up on its toe in part of a revolution of the frame and back on its heel in the other part of the revolution. Such rocking action causes the scraper blade to act as a cutting tool which gouges, cuts or scores the shell wall. Further, since the hydraulic loads in the scraping operation are high and as the rocking motion of the scraper blade reduces the bearing area, gauling also occurs. To further aggravate this problem, more viscous greases are being currently manufactured and such added viscosity increases the load on the blade and causes failure more often.

In a recent attempt to eliminate such costly described damage to the kettle shell, a blade had been provided wherein the blade shoe was ground to a smaller radius than the internal radius of the kettle shell so as to prevent the toe or heel from coming against the shell during the travel of the blade shoe around the shell. Such a blade eliminated the damage to the shell but actual tests showed that the heat transfer rate had been reduced approximately 40% in such an application. This lowering of the heat transfer rate was caused by the blade design which, after reduction of the blade shoe radius, no longer acted as a knife edge in scraping grease from the wall but actually 2,834,977 Patented May 20, 1958 rode on a grease film as it traveled around the inside wall of the kettle. Thus, although the failures due to scoring and machining of the kettle shell were eliminated an ineflicient scraping blade was produced.

Therefore, an object of the present invention is to provide a free-floating, self-adjusting scraper blade having freedom of translation relative the driving scraper frame for use in grease manufacturing kettles which will automatically allow for eccentric motion of the driving scraper frame without changing the scraper blades position relative the internal wall of the kettle.

Another object of the invention is to provide a scraper blade assembly wherein the scraper blade is driven by radial pins rigidly attached relative the rotating scraper frame, said radial pins so fixed in position as to exert only a component force in the direction tangent to the circular motion described by the scraper blade.

Another object of the invention is to provide a scraper blade assembly wherein the point of application of driving force to the scraping blade is placed more directly behind the center of the resisting hydraulic force and more nearly coaxial to this force, thus reducing the radial component of the hydraulic force which pushes the blade against the shell and thereby relieving the pressure on said shell.

Another object of the invention is to provide a scraping blade comprising a double contact unit having a blade contact and a divided tail contact with the internal kettle surface, the non-continuous tail portion of the blade thus allowing grease which may get under the blade a path of escape.

Still another object of the present invention is to provide a double contact scraping blade having a toe and a heel contact with the internal surface of the grease kettle, the areas of the toe and heel of the blade which contact the shell so designed as to give substantially equal wear in order that the blade unit or shoe will not change its position (other than its distance from the center of the vessel) due to wear.

Other and further objects of the invention will appear in the course of the following descritpion.

In the drawings, which form a part of the instant specification and are to be read in conjunction therewith, an embodiment of the invention is shown and, in the various views, like numerals are employed to indicate like parts.

Fig. 1 is a side sectional view of a scraper blade assembly for use in grease manufacturing kettles embodying the present invention and is a view taken along the lines 1-1 of Fig. 2 in the direction of the arrows.

Fig. 2 is a plan view of the scraper blade assembly shown in Fig. 1.

Referring to the drawings, the numeral It designates a scraper frame having scraper drive plate 11 fixedly mounted thereon. Frame lll has threaded openings 10a near the front end thereof and drive plate ll has openings 11a near its rear edge to receive bolts 12. Shims i 13 permit precise adjustment of plate 11 on frame 10.

The frame is adaptable for mounting on any conventional radial driving arms or impellers (not shown) for driving the blade assembly in its circular motion relative the internal surface of a grease kettle shown at 14.

' Scraper drive plate 11 is mounted axially of frame It) and extends past the end thereof in the direction of rotation. Drive plate 11 has raised portions 15 on the inner surface thereof having openings 16 therethrough and spring receiving cavities 17 in the outer side thereof. Scraper blade 18 preferably is formed in cross section as a shoe having two areas of contact with the interior surface of kettle wall 14. Toe portion 19 of shoe 18 is preferably of knife edge design and heel or tail portion 20 is divided or non-continuous to permit grease which may get plate,,0p ening 16. The tolerance bet-wcemflle outer; diam-- eter of, pins,2.2, and the inner diameters ofyopeningsfll is such. as. tosallow. sufiicient angular deflection; of: the; blade shoe around its two non-radial axes to.compensatefor any, ordinarily encountered irregularities in. thekettle. It. is, contemplated-that an allowed. rotation of plus, 01" minus, onequarter of. a degree (MN) around the nonradial axes together with the in and out radial motion,

(translational motion) would compensate completely, for

any. such kettle surface irregularities. Such rotationds. not intended to be limitingbut illustrative-only. The.

bladeshoe 1 8 .is. ground to the radius of the shell 14. at its Point of contact therewith. The areas of tl1e,toe,;19' and. tail 20,whic h contact the inner surface of the kettle wall are preferably so designed as to give-substantially equal wear so that blade shoe 18- will not change-its position (other than its distance-from the center of the vessel) due to wear.

The means for mounting blade shoe, 18 relative said drive, plate, 11 cooperate therebetween so. as to permit the blade to allow for eccentric motion of the, driving scraper frame 10.without changing-the. position. of the blade relative, the kettle wall. This mounting means comprises pins 22 and resilient means 23 cooperating between the blade shoe 18 and drive plate 11 which permit-shoe 18. to be essentially free-floating and. self-adjusting in translational motion relative the inner. surface of the kettle wall.,14. Pins 22 are so fixed in .positionrelative shoe 18 as to exert only a component force in-the direction,tangent to the circle described by; the motion oflthe blade. The point of application of driving force-be: tweempins 22. and shoe 18 is placed essentially directly behind the, resistinghydraulic force (of the 1 grease and,

the kettle wall) and essentially coaxial to the latter force.

The radial component-of the hydraulic force. which pushes the blade against the shell is thus reduced and thus the. pressure on the shell also. Resilient meansv 23 preferably comprises. coil springs which encircle pins 22,, abut, at

their end faces drive plate 11 and. shoe 18andare-re.

ceivedattheir inner ends in cavities 17.

In operation, scraper drive. plates 11 are fixedly at-v tached. to conventional scraper frames 10Iin a gl'fiase kettlehaving conventional scraper frame drivingv means- Scraper blade; shoes.

(notshown) radial to the frames. 18, are mounted-on pins 22 with resilient means-23 act ing betweentshoes-ls and driveplates 11 to make shoes ISIfree-floating and self-adjusting in translational mo tionrelative thereto. When force is applied to frame 10.

to drive it in circularmotion around Wall 14, shoe 18 will ride on the vessel wall, held there lightly by spring pressure. Shoe 13 will not change its position relative wall 14 in its motion because of eccentric motion. of the scraper frame due to. its freedom of'translationalmotion relative thereto and thus, due to the double resilient support of shoe 18, the-blade will not rock upon its we in part ofarevolution and back on its-heel in the. other part if the frame motion is eccentric relative-the-kettle wall.

From the foregoing it will-be seen that this invention, is-one well adapted to attain all of the ends, andzobjects hereinabove set forth together with other advantages:

which are obvious and which are inherent to the. structure.

It will be understood that certain features and-sub:

combinations are of utility and may be employed without having heel and toe contact portions whereby to contact the interior surface of thekettle on at least two portions thereof, a. scraper frame, a. scraper drive plate fixedly mounted onan-end of; said frame and'at least partially overlying said blade, said plate having a lower faceladjacent said" blade and an-upper face away therefrom, the upper face of the toe' portion of saidblade angled upwardly from the lower kettle contacting face of said toe portion, the forward edge of saidplate approaching the toe'area of the. blade,.and mounting means cooperating between the drive plate and blade so as to permit the blade tanslational motion relative the drivev plate and driving scraper frame without changing the at least substantially flat abutment of the blade on the kettle. wall independent of any. eccentric motion of the scraper frame relative the kettle wall.

2; A scraper blade assembly as in claim 1 wherein the width. of the portion of the plate adjacent the toe of the blade is substantially that of the blade toe.

3: A scraper blade as in claim 1 wherein the width of the plate is substantially that of the blade toe.

4t Ascraper blade assembly as in claim 1 wherein the upper face of the plate is angled relative the contact surface of the blade toe substantially the same as the upper surface of the blade. toe.

53 A scraper blade assembly as in claim 4 wherein the lower. face. of the plate adjacent the blade toe is beveledto permit. a closer approach of the plate to the blade without; contact therebetween.

the upper face of the plate is angled relative the contact surface of the blade toe substantially the same as the upper surface of the blade toe.

8. A scraper blade assembly as in claim 6 wherein the upper. face of the plate is angled relative the contact surface of the blade toe substantially the same as the upper surface of the blade toe and the lower face of the plate adjacent the toe of. the blade is beveled to permit a closer approach of, the plate to the blade without contact therebetween.

9,. A scraper blade assembly for scraping "the interior surfaces of grease kettles comprising a scraper frame, a scraper drive plate fixedly. mounted to an end of said frame, a scraper blade, said blade. having a leading toe portion and'a following heel portion giving two areas of contact between the blade and the kettle wall, means for mounting said blade relative said drive plate, said mounting means cooperating between said drive plate and saidblade so as to permitthe blade to allow for eccentric motion of the driving scraper frame relative the kettle wall without changing the blades position relative the kettle wall, said mounting means comprising a pair of nadial'pins, said pins fixedly engaging the drive plate and removably received in openings betweenthe heel and toe portions ofthe blade, said'openings lying axially substantially in the same diametrical plane of the kettle, the pins bearing. on the walls of the openings in the blade to drive the blade, andresilient'means cooperating be.- tween said blade and said drive plate to permit the blade translational motionrelative said drive plate and said kettle. interior wall.

References Cited in the-fileofthis patent UNITED STATES PATENTS 980,444- Sleeper Ian.- 3, 19-11- l,'23l,695'- Bell July 3, 1917' 2,323,907 Ham'ss July 13; 1943 

